Rotary sheet transfer members having engageable toothed sectors in proximity to sheet grippers

ABSTRACT

A printing press comprises a plurality of gripper carrying rotary impression and transfer cylinders play which paper sheet to be printed are transferred. Each cylinder has a pair of lateral discs and each disc has mounted thereon a toothed sector adapted to cooperate with the toothed sector mounted on one of the lateral discs of a cooperating cylinder during each step of exchange of a sheet. The sectors of each cooperating pairs thereof being preferably different in pitch radii and being so made as to have one pair of elements only, namely one tooth and a pair of teeth, respectively which intermesh without play during the said step of exchange. The remaining teeth having variable play during interengagement of the sectors, growing with the distance from the above said elements.

Inventors Paolo Papa;

Federico Cappetti, Turin, Italy 730,546

May 20, 1968 Jan. 19, 1971 Societa Nebiolo S.p.A.

Turin, Italy Oct. 14, 1967 Italy No. 53353-A/67 Appl. No. Filed PatentedAssignee Priority ROTARY SHEET TRANSFER MEMBERS HAVING ENGAGEABLETOOTI-IED SECTORS IN PROXIMITY T0 SHEET GRIPPERS 9 Claims, 3 DrawingFigs.

US. Cl. 101/232, 101/248, 101/246, 74/440, 271/69 Int. Cl. ..Fl6h 55/18,B6511 5/12 Field 01 Search 101/248, 137, 142, 183, 217, 232, 246;74/409,440; 271/69 References Cited UNITED STATES PATENTS 6/1906 Berry101/248 1,498,653 6/1924 Harrold 101/248 2,767,652 10/1956 Dietrich etal.. 101/248 2,887,046 5/1959 Knops et al. 101/248 FOREIGN PATENTS516,885 1/1931 Germany 101/248 1,124,053 2/1962 Germany 101/183 PrimaryExaminerRobert E. Pulfrey Assistant ExaminerJ. Reed FisherAttorney--Sughrue, Rothwell, Mion, Zinn and Macpeak ABSTRACT: A printingpress comprises a plurality of gripper carrying rotary impression andtransfer cylinders between which paper sheet to be printed istransferred. Each cylinder has a pair of lateral discs and each disc hasmounted thereon a toothed sector adapted to cooperate with the toothedsector mounted on one of the lateral discs of a cooperating cylinderduring each step of exchange of a sheet. The sectors of each cooperatingpairs thereof being preferably different in pitch radii and being somade as to have one pair of elements only, namely one tooth and a pairof teeth, respectively which intermesh without play during the said stepof exchange. The remaining teeth having variable play duringinterengagement of the sectors, growing with the distance from the abovesaid elements.

SHEET 1 OF 3 PATENTED JAN 1 91971 mgmguqmzsmn 3,556,006

SHEET 2 OF 3 Fig.2

PATENT EU JAN] 9 {97! SHEET 3 OF 3 The invention relates to printingpresses of the type wherein the paper sheets are transferred bet'ween aplurality of rotary members.

lt is known that more particularly in printing presses for multicolorsheets, comprising a plurality of components each including animpression cylinder an a number of transfer cylinders, all provided withgrippers which mutually exchange the sheets being printed, the lattershould be exchanged between one component and the next so as to beconstantly presented to the various impression cylinders in the sameposition in order to successively print thevarious colors constantly atthe predetermined positions or in register.

A condition for maintaining register is accurate retaining of the sheetby, the grippers on the various cylinders during withdrawal, transportand delivery to the next cylinder.

A further condition is a correct mutual positioning of the two sets ofgrippers effecting the exchange. Any offset from the mutual position ofthe grippers on one cylinder or between the grippers on thecylinderreceiving the sheet and the cylinder delivering the sheet,respectively, occuring during exchange, detrimentally affects quality ofthe register. l i

In order to. obviate this drawback it was proposed to provide inproximity to the grippers cooperating in exchange, in addition toconventional cylinder driving gears, a pair of structural members havingconjugated profiles, or to provide on the cooperating driving gearspairs of toothed sectors fixedly secured thereto, or still to provide onthe said gears toothed sectors one of which isrigidly fixed to a gearandthe other is resiliently connected to the second gear.

All the above arrangements which merely aimed at taking up play betweenthe sets of teeth in the gears rotating contiguous cylinders, do notsolve the registerproblem, inasmuch as the above mentioned plays, thoughobjectionable are neither alone nor by a major part responsible forregister inaccuracies. It was ascertained that the latter are mainly dueto vibrations and twist of the cylinders or other rotary members betweenwhich the sheets are exchanged during operation of the printing press.

An object of the invention is to'provide a rotary printing press havinga plurality of rotary members between which the sheets are exchanged,wherein vibrations and torsional stressesv on these members so not leadto inaccuracies in register.

The invention provides to this effect on the lateral discs of the rotarymembers of the press carrying the grippers, pairs of toothed sectorsadapted to cooperate by pairs during the exchange step, of aconfiguration such that during this step to the vibrations and/ortorsional stresses of one rotary member there correspond similarvibrations and/or torsional stresses of its cooperating rotary member.

According to a preferred embodiment of the invention the sectors areshaped so that at the start and end of the meshing step of the sectorsof each pair a maximum play exists between their respective teeth, whichgradually decreases till it is annulled at their middle zone over an arcthe length of which is selected in accordance with the period of time ofthe exchange step.

The sectors may conveniently have a modular and circular set of teethand differ in pitch radii. The sector of the larger pitch radius isconcentrically mounted on its respective rotary supporting member,thesector of smaller pitch radius being eccentrically mounted with respectto the axis of the otherrotary member cooperating with the former. v

Further characteristic'features and advantages of the invention will beunderstood from the appended description referring by way of example toan embodiment shown on the accompanying drawings, wherein:

H6. 1 is a diagrammatical side elevational view of a machine accordingtothe invention comprising two printing members;

FIG. 2 is a sectional view on line II-Il of FIG. I on an enlarged scale;v FIG. '3 is a side view of a pair of cooperating sectors each mountedon one of the contiguous rotary members provided with grippers, betweenwhich the sheets are exchanged.

On the drawings, 1 and 2 denote the two printing elements forming atwo-color' sheet printing press. Each element comprises an impressioncylinder 3 cooperating with a rubber cylinder 4 which is in contact witha further cylinder 5 carrying a plate (not shown) which is engraved andinked in a I manner known per se..

Sheet transfer cylinder 6, 7, 8, respectively, are interposed betweenthe impression cylinders 3 of the elements 1, 2, respectively. Theimpression cylinder of the element 2 receives sheets fromthe oscillatinggrippers diagrammatically denoted by 9, the impression cylinder 3 on theelement 1 delivering the sheets to the outlet chain diagrammaticallydenoted by 10.

The impression cylinders 3 and transfer cylinders 6, 7 and 8 carry attheir lateral discs lls, 11d and 12s, 12d, respectively (FIG. 2) toothedsectorsl3's, l3'd and 13s, I3d, respectively, the former only beingvisible in FIG. 1. The cylinders 3, 6, 7 and 8 are so positioned thatthe toothed sectors on contiguous cylinders cooperate togetherthroughout the exchanges carried out by means of grippers 23, 24 (FIG.3), in which the cylinders are involved.

As will be seen in FIG. 2, the cylinders are carried by shafts 14rotatably 'mounted in supports 15 driven into the opposite sidewalls 16of the machine frame. The shafts 14 of the cylinders 3, 8 are keptagainst axial displacement by known devices, not shown.

The cylinders are rotated through their driving gears 17 keyed to theends of the shafts 14 extending beyond one of the sidewalls 16 andforming a kinematic chain leading to a driving motor for the machine(not shown).

The toothed sectors 13s and 13's, 13d and l3'd of each of thecooperating sector pairs such as the sectors mounted on the lateraldiscs of the cylinders 3, 8 respectively, though being both circular andmodular, differ in pitch circles. As will be seen in FIG. 3, the sector13's mounted on the lateral disc 11s of the impression cylinder 3 of thefirst element has its center situated on the rotational axis C of thecylinder 3, the sector 13: mounted on the lateral disc 12.: of thecylinder 8 having its center situated a distance e apart from therotational axis C of the cylinder 8.

The sectors are provided with one pair only, of elements namely thetooth l8 and the teeth 19 which intermesh without play during theexchange of the sheets, the remaining teeth meshing with a'graduallyvariable play.

By this structure as cooperation of the two sectors starts graduallydecreasing plays exist on the flanks of the consecutive teeth, and areannulled when the tooth 18 starts meshing in the hollow between theteeth 19, exactly at the region where the pitch circle of a sector istangential to the pitch circle of the other sector. At the end of theexchange step the play between the teeth of the two sectors againgradually increases till full mutual disengagement of the sectors.

As further shown in FIG. 3, Rp and R'p are the radii of curvature of thepitch circles of the gears 17 keyed to shaft 14 carrying the cylinders 8and 3, respectively; rp is the radius of the pitch circle of the toothsector 13s; and P, and P, are the rotational axes of the grippers 24 and23, respectively.

By the above-described structure the cooperation of the sectors takesplace in the absence of shocks even at high rates of speed and anyangular offset of the two cylinders between which exchange occurs istaken up in the absence of objectionable vibrations. The structure is.advantageous in simplicity of construction and assembly, inasmuch as thesectors are partsof modular, gears currently manufactured and theirassembly on the lateral discs of the cylinders can be carried outwithout necessitating expensive apparatus and in a short time.

The sectors 13's and l3'd that are concentric with the axis of thecylinder 3 preferably are mounted on the cylinder 3 in such manner thattheir pitch circles are the same as the pitch circle of the driving gear17 for the cylinder 3. Each of the other sectors 13s and 13d are somounted on the cylinder 8 such that the tooth l8 accurately fits,substantially without clearance, into the hollow between the teeth 19 ofthe corresponding sector at the point of tangency of the sectors. Thisis accomplished by the positioning pins 20 and 21 which engage the innerperiphery of each of the sectors 13s and 13d, which may be locked inposition by the locking screws shown in FIG. 3 or by any other suitablemeans. Each of the sectors 13s and 13d are adjustable relative to thepositioning pins 20 and 21 by providing holes (not shown) therein whichare larger than the shanks of the locking screws. if the sectors 13s and13d are to be positioned in spaced relation to the pins 20 and 21, thespacing between each of the sectors and the pins should be substantiallyequal in order to properly orient the sectors on the cylinder 8.

We claim:

1. in printing press of the type comprising a plurality of rotarymembers between which a sheet to be printed is transferred, a gripper oneach of said rotary members for retaining a sheet thereon when it istransferred thereto from another rotary member, a pair of lateral discsmounted on the sides of each rotary member, and a driving gear rotatableabout the rotary axis of each rotary member and secured thereto inspaced relation therewith. the driving gears for cooperating rotarymembers being constantly intermeshed; the improvement comprising acurved toothed sector mounted on each of said lateral discs in proximityto the gripper on the corresponding rotary member. the pair of sectorsmounted on the lateral discs of one rotary member being positionedgradually to engage and then disengage the pair of sectors mounted onthe lateral discs of an adjacent rotary member as a sheet is beingtransferred from a gripper on said one rotary member to a gripper onsaid adjacent rotary member. the pitch circles of said pairs of sectorsbeing tangential at the point at which a sheet is transferred from thegripper of said one rotary member to the gripper of said adjacent rotarymember.

2. The printing press as claimed in the claim 1, wherein the sectors ofsaid adjacent rotary member are of variable curvature with respect tothe rotational axis of said adjacent rotary member.

3. The printing press of claim I wherein the pitch radii of the sectorsof said one rotary member are larger than the pitch radii of the sectorsof said adjacent rotary member, the sectors of said one rotary memberbeing concentrically mounted on the lateral discs thereof, and thesectors of said adjacent rotary member being eccentrically mounted withrespect to the axis of the lateral discs thereof.

4. The printing press of claim 1 wherein the pitch radii of the sectorsof said one rotary member are equal to the radius of the driving geartherefor.

5. The printing press of claim 1 wherein the pitch radii of the sectorsof said one rotary member are less than the radius of the driving geartherefor.

6. The printing press of claim 1 wherein the pitch circles of thesectors of said adjacent rotary member are tangential to the pitchcircle of the driving gear for said one rotary member.

7. The printing press of claim 1 wherein each of the sectors of saidadjacent rotary member has one tooth that is adapted to fitsubstantially without clearance between a pair of teeth of thecorresponding sector of said one rotary member at the point at which asheet is transferred from the gripper of said one rotary member to thegripper of said adjacent rotary member.

8. The printing press of claim 6 wherein the pitch circles of thesectors of said one rotary member are tangential to the pitch circle ofthe driving gear for said adjacent rotary member.

9. The printing press of claim 7 wherein the remaining teeth on each ofsaid sectors of said adjacent rotary member are arranged symmetricallywith respect to said one tooth and are adapted to gradually engage withclearance and then gradually disengage the teeth of the correspondingsectors on said one rotary member when said sectors on said one and saidadjacent rotary members are engaged during the transfer of a sheet.

1. In printing press of the type comprising a plurality of rotarymembers between which a sheet to be printed is transferred, a gripper oneach of said rotary members for retaining a sheet thereon when it istransferred thereto from another rotary member, a pair of lateral discsmounted on the sides of each rotary member, and a driving gear rotatableabout the rotary axis of each rotary member and secured thereto inspaced relation therewith, the driving gears for cooperating rotarymembers being constantly intermeshed; the improvement comprising acurved toothed sector mounted on each of said lateral discs in proximityto the gripper on the corresponding rotary member, the pair of sectorsmounted on the lateral discs of one rotary member being positionedgradually to engage and then disengage the pair of sectors mounted onthe lateral discs of an adjacent rotary member as a sheet is beingtransferred from a gripper on said one rotary member to a gripper onsaid adjacent rotary member, the pitch circles of said pairs of sectorsbeing tangential at the point at which a sheet is transfeRred from thegripper of said one rotary member to the gripper of said adjacent rotarymember.
 2. The printing press as claimed in the claim 1, wherein thesectors of said adjacent rotary member are of variable curvature withrespect to the rotational axis of said adjacent rotary member.
 3. Theprinting press of claim 1 wherein the pitch radii of the sectors of saidone rotary member are larger than the pitch radii of the sectors of saidadjacent rotary member, the sectors of said one rotary member beingconcentrically mounted on the lateral discs thereof, and the sectors ofsaid adjacent rotary member being eccentrically mounted with respect tothe axis of the lateral discs thereof.
 4. The printing press of claim 1wherein the pitch radii of the sectors of said one rotary member areequal to the radius of the driving gear therefor.
 5. The printing pressof claim 1 wherein the pitch radii of the sectors of said one rotarymember are less than the radius of the driving gear therefor.
 6. Theprinting press of claim 1 wherein the pitch circles of the sectors ofsaid adjacent rotary member are tangential to the pitch circle of thedriving gear for said one rotary member.
 7. The printing press of claim1 wherein each of the sectors of said adjacent rotary member has onetooth that is adapted to fit substantially without clearance between apair of teeth of the corresponding sector of said one rotary member atthe point at which a sheet is transferred from the gripper of said onerotary member to the gripper of said adjacent rotary member.
 8. Theprinting press of claim 6 wherein the pitch circles of the sectors ofsaid one rotary member are tangential to the pitch circle of the drivinggear for said adjacent rotary member.
 9. The printing press of claim 7wherein the remaining teeth on each of said sectors of said adjacentrotary member are arranged symmetrically with respect to said one toothand are adapted to gradually engage with clearance and then graduallydisengage the teeth of the corresponding sectors on said one rotarymember when said sectors on said one and said adjacent rotary membersare engaged during the transfer of a sheet.